Circuit breaker with improved terminal-conductor means



Oct. 18, 1966 J. P. ELLSWORTH ETAL 3,280,287

CIRCUIT BREAKER WITH IMPROVED TERMINAL-CONDUCTOR MEANS Filed May 1965 2 Sheets-Sheet 1 "OFF-I 8| F|g.l.

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INVENTORS James P. Ellsworth Glenn R.Thomus BY 9%M 4 66M ATTORNEY Oct. 18, 1966 J. P. ELLSWORTH ETAL Filed May 10, 1963 2 Sheets-Sheet 2 United States Patent 3,280,237 CIRtJUiT BREAKER WITH IMPROVED TERMINAL-CONDUtITflR MEANS James P. Elisworth and Glenn R. Thomas, Beaver, la.,

assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed May 10, 1963, Ser. No. 279,368 12 Claims. (Cl. 2t)0147) This invention relates generally to circuit interruzpters and more particularly to bolt-on type circuit breakers for panelboards and control centers.

A general object of this invention is to provide an improved circuit breaker comprising a minimum of parts and having parts that serve a plurality offunctions.

Another object of this invention is to provide an improved bolt-on type circuit breaker for panelboards;

Another object of this invention is to provide an improved circuit breaker comprising a line terminal conductor with improved means fastening the line terminal conductor in position;

The invention, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read in conjunction with the accompanying drawings.

In said drawings:

FIGURE 1 is a side sectional view of a circuit breaker embodying principles of this invention, the breaker beingshown in the closed position;

FIG. 2 is a side sectional view of part of the circuit breaker seen in FIG. 1, the contacts being shown in the open position;

FIG. 3 is a partial sectional view of one pole unit taken generally along the line lIlIlI of FIG. 1;

FIG. 4 is a sectional view taken along the line IV-IV of FIG. 1;

FIG. 5 is a sectional view of a panelboard having circuit breakers embodying principles of this invention mounted thereon;

FIG. 6 is a partial sectional view of a circuit breaker and illustrating a modification of the invention seen in FIG. 1; and

FIG. 7 is a sectional view taken along the line VII-Nil of FIG. 6.

Referring to the drawings, a circuit breaker 3, shown in FIG. 1, is of the same general type that is more specifically shown and described in the copending patent application of James P. Ellsworth and Robert H. Flick, Serial No. 846,939, filed October 16, 1959, and assigned to the assignee of the instant application.

Only the center pole unit of the multi-pole circuit breaker is herein described. The present invention is embodied in each of the pole units in the same manner as in the center pole unit. Moreover, the present invention can also be embodied in single-pole circuit breakers wherein the single-pole unit is similar to that shown and illustrated in FIG. 1.

The circuit breaker 3 comprises a housing of molded insulating material, which housing comprises a base 11 and a cover 13. In a multi-pole circuit breaker the housing 11, 13 comprises a plurality of adjacent insulating compartments wherein each compartment comprises a stationary contact 15, a movable contact 17, an operating mechanism indicated generally at 19 and a trip device indicated generally at 21.

The stationary contact is mounted on the inner end of a flat and generally rigid line terminal conductor 23 that is secured to the base 11 by fastening means indicated generally at 25 and comprising a nut 27 of magnetic material such as magneticsteel and a screw 29 of magnetic material such as magnetic steel. As will be hereinafter specifically described, the fastening means 25 also serves as an arc-runner to enhance extinction of arcs drawn between the contacts 15, 17. An opening 31 (FIG. 3) is provided in the outer end of the terminal conductor 23 to receive a fastening screw 33 (FIG. 1) that connects the terminal conductor 23 to a conducting connector 35. The screw 33 threadedly engages in a tapped opening in the connector 35. The movable contact 17 is rigidly secured to a U-shaped switch or contact arm 37 that is manually operated to open and closed positions by operation of the operating mechanism 19.

The operating mechanism 19 comprises a molded insulating operating member 39 having an external handle portion 41, an overcenter spring 43 and a releasable trip member 45. The operating member 39 is rotatably supported on side walls of the cover 13. One end of the releasable trip member 45 is embedded in an insulating support 47 that is rotatably supported on the sidewalls of the housing 11, 13. The overcenter spring 43 is supported, under tension, at one end in an opening in the bight portion of the U-shaped contact arm 37, and at the other end in an opening 51 in the releasable trip mem ber 4-5. The spring 43 biases the trip member 45 in a counterclockwise (FIG. 1) direction, which movement is restrained by means of the trip device 21. As is shown in FIG. 1, the spring 43 biases the contact arm 37 to the closed position.

The circuit breaker is opened manually by counterclockwise movement of the handle 41 from the ON position to the OFF position. During this movement, the outer or upper ends 53 of the U-shaped switch arm 37, which ends are positioned in suitable notches in the operating member 39, are carried over to the right of the line of action of the overcenter spring 43, whereupon the spring moves the switch arm 37 to the open position, shown in dot and dash lines, with a snap action. The contacts are closed by reverse movement of the operating handle 41', during which movement the outer or upper ends 53 of the switch arm 37 are moved over to the left of the line of action of the overcenter spring 4-3, which spring then moves the switch arm 3'7 to the closed position with a snap action.

The trip member 45 is released, to effect automatic opening of the contacts, by operation of the thermal magnetic trip device 21. The trip device 21 comprises a bimetal 55 that is welded or otherwise attached to an arm portion of a terminal conductor 57, which conductor extends out from the housing 11, 13 and is threadedly engaged by a screw 59 to permit connection of the circuit breaker in an electric circuit. A magnet member 61 is secured to the lower or free end of the bimetal 55. An armature 63 is positioned adjacent the magnet member 61. The armature 63 is pivotally supported, intermediate its ends, in notches 65 in metallic pivots 67. A metallic strip 69 is secured to the lower end of the armature 63. The strip 69 is shaped to engage a button 7t on the magnet member 61. The free end of the releasable trip member 45 engages a ledge portion in an opening in the armature 63 to be held in the latched position seen in FIG. 1. An adjusting screw 71 is provided to permit adjustment of the normal position of the bimetal 55 to thereby permit calibration of the circuit breaker.

When the circuit breaker is in the closed position seen in FIG. 1, a circuit extends from the conducting connector 35 through the terminal conductor 23, the stationary contact 15, the movable contact 17, the contact or switch arm 37, a flexible conductor 75, the bimetal 55, the terminal conductor 57 to a conductor that would be secured to the conductor 57 by means of the screw 59.

Upon the occurrence of an overload current below a predetermined value, the bimetal 55 is heated and it flexes to the left moving the magnet member 61 and the member 69 to the left to move the armature 63 in a clockwise direction about the pivots 65 to release the trip member 45. When the trip member 45 is released, the spring 43 rotates the trip member in a counterclockwise direction until the trip member is arrested by engagement thereof with a molded projection 77. During this movement, the line of action of the spring 43 is moved to the left of the pivot 53 of the switch arm 37, whereupon the spring 43 operates to move the switch arm 37 to the open position With a snap action. During this movement of the spring 43 and switch arm 37, the operating member 39 is moved to move the handle 41 to an indicating position between the on and oil positions in a manner well known in the art.

Before the contacts can be closed following an automatic opening operation, it is necessary to reset and reiatch the mechanism. This is accomplished by moving the handle 41 to the full oil position. During this movement, a leg portion 79 of the operating member 39 engages a pin S1 that is secured to the trip member 45, to move the trip member 45 back to the position in which it is latched by the armature 63 that is biased to the latching position by spring means (not shown). Thereafter, the circuit breaker can be operated in the same manner hereinbefore described.

Upon the occurrence of an overload current above the predetermined value, the magnet member 61 is energized sufiiciently to instantaneously attract the armature 63 to release the trip member 45 and effect opening of the circuit breaker in the same manner previously described.

As the contacts 15, 17 open, an arc is drawn between the contacts, which are is extinguished to interrupt the circuit controlled by the circuit breaker. An arc extinguishing structure indicated generally at 83 is provided to enhance rapid extinction of these arcs. The arc extinguishing structure 83 is most useful when the circuit breaker automatically interrupts heavy overload or short circuit currents. The are extinguishing structure 83 comprises an insulating arc wrapper 85 to which is secured a plurality of generally U-shaped arc plates 87 of magnetic material such as magnetic steel. The are wrapper 85 comprises atail portion 89 that is engaged by the fastening means 25 to hold the arc extinguishing structure 83 in place. As can be seen in FIG. 3, notches 91 are formed in the insulating base ll'during the molding operation of the base. When the circuit breaker is assembled, the arc extinguishing structure 83 is placed down into position in the base 11 and, thereafter, the nut or are runner 27, which has a greater width (FIG. 3) than height (FIG. 2), is dropped down into the slots 91 (FIG. 3) to rest upon the tail portion 89 (FIGS. 1 and 2) of the arc wrapper 85. The terminal conductor 23, with the stationary contact attached thereto, is then placed in position and a portion thereof extends through an opening 93 in the base 11. The terminal conductor 23 rests on a molded portion 95 of the base 11. When the terminal conductor 23 is in position, the screw 29 is passed through a suitable opening in the conductor 23 and is threaded into the tapped opening in the nut 27. The fastening means 25 holds the conductor 23 and the arc extinguishing structure '83 in the positions in which they are seen in FIG. 1. After the terminal conductor 23 is fastened in place, an insulating barrier 96 is placed upwardly into slots (FIG. 3) in the housing base 11 and cemented in place.

In addition to holding the terminal conductor 23 and are extinguishing structure 83 in place, the fastening means 25 also serves as an arc-runner during circuit interruption. As was hereinbefore described, an arc is drawn between the contacts 15, 17 during each opening operation and, in the case of an interrupt-ion of a severe overload current, it is important to extinguish the are as rapidly as possible. As the arc is drawn between the opening contacts, the magnetic lines of force generated around the arc operate through the U-shaped magnetic steel plates-87 to draw the arc downward into the plates, whereupon the arc is broken into a plurality of serially related arcs to be extinguished in a manner well known in the art. The are 97 is shown as a full line in FIG. 2, just prior to the time when it is broken up into a plurality of serially related arcs, and in broken lines just after it is broken up into a plurality of serially related arcs and just prior to extinction thereof. The magnetic steel nut or arc-runner 27 attracts the arc and as the arc is pulled into the arc plates 87 it is transferred from the contact 15 to the member 27. As the arc moves down into the arc plates 87, a part 99 (FIG. 2) thereof that is transferred to the arcrunner means 27, 29 moves down the member 27 and the inner end of the magnetic steel member 29. It is to be noted that the arc-receiving surfaces of the arc-runner means 27, 29 are disposed below the separating contacts and on the side of the contact 15 that is opposite the side that engages the movable cont-act 17. Thus, as the arc is drawn into the plates 87, when it is transferred from the stationary contact 15 to the arc-runner means 27, 29 it is elongated because it moves in a downward direction away from the movable contact 17, and it is additionally elongated because it moves in a lateral direction away from the movable contact 17. This rapid and elongating movement of the am into the arc plates 87 enhances rapid extinction of the arc.

As was previously described, the circuit breaker 3 can be either a single-pole circuit breaker or a mu lti-pole circuit breaker. If the circuit breaker is a single-pole circuit breaker, the one pole unit will be just like the pole unit seen in FIG. 1, and the barriers B (FIG. 3) will be the external sidewalls of the breaker. If the circuit breaker is a m-ulti-pole circuit breaker, only one pole unit thereof will be identical to the pole unit seen in FIG. 1. The other pole units will be just like that seen in FIG. 1 except that they will not include an external operating handle 41, and the members 45 of the other pole units will not have a latching end latched on an armature. Only the member 45 in the center pole unit is latched. If, for example, the circuit breaker is a three-pole breaker and the part seen in FIG. 3 is the center pole unit, the barriers B will separate the adjacent compartments. In the multi-pole circuit breaker, the member 39 will extend through each compartment in the circuit breaker to function as a common operating member operated by the single external operating handle 41. The member 47 will extend through a l of the compartments to operate as a common member, and the arm-atures 63 of all of the pole units will be connected by insulating means to function as a common trip device. Thus, when any one of the armatares 63 is moved to a tripping position they will all move to the tripping position as a unit to thereby release the member 45 in the center pole unit whereupon the common member 47 will be operated by the springs 43 in all oi the pole units and all of the switch 'arms 37 will be moved to the open position. During manual operation, when the single external operating handle 41 is operated, the common member 39 will move tosimultaneously move all of the springs 43 and switch arms 37 to eifect simultaneous opening and closing of all of the switch arms 37 in all of the pole units.

Referring to FIG. 5, there is shown therein a panel-- board of the type more specifically described and claimed in the copending application of J. P. Ellsworth et al., Serial No. 279,366, filed May 10, 1963, and assigned to the assignee of the instant application. The applica tion is referred to as W.E. Case 34,868. The panelboard 105 comprises a base pan 107 and an insulating mounting or support block 109 mounted on the base pan 107. The support block 109 has three transverse slots in the back thereof for receiving three bus bars A, B and C. As is more specifically described in the above-mentioned copending application, the support block 109 is provided with three adjacent longitudinal cavities and three conducting connectors. Each conducting connector is disposed in a different cavity and each is connected to a different one of the bus bars. The conducting connector 35, seen in FIG. 5, is connected to the bus bar C by means of a screw 111. Each of the conducting connectors 35 is a rigid member having a flat base with two openings therein each of which openings is tapped to receive a screw 33 for connecting a line terminal conductor 23 to the conducting connector 35. Each of the circuit breakers 3 is mounted at the load end thereof on a ledge 115, of the insulating support block 169. A plate 117 is secured to each end of the mounting block 109 and it is provided with an extension 119 that fits over a clip 121 (FIG. 1) that is secured to the circuit breaker housing to thereby prevent upward movement of the load end of the circuit breaker. As can be seen in FIG. 5, each of the conducting connectors 23 extends out from the bottom of the circuit breaker 3 in a direction normal to the bottom of the breaker and it is bent to provide an end portion that is generally parallel to the bottom of the circuit breaker which end portion rests on the conducting connector 35 to fixedly support the line end of the circuit breaker 3 on the conducting connector 35 and to electrically connect the circuit breaker contacts with the conducting connector 35. Each of the line terminal conductors 23 is a generally flat and generally rigid member for adequate support. As is best seen in FIGS. 1 and 4, two reinforcing ribs 125 are formed in the conducting member 23, by means of a stamping operation, in proximity to the external bend therein to strengthen the member and thereby prevent easy distortion of the member 23.

An insulating barrier 129 is provided on each of the two opposite sides of each of the three longitudinal cavities. The barriers 129 are molded integnal with the support block 109. It is desirable to keep the end parts 130 of the barriers 129 relatively thin. Thus, when a multi-pole circuit breaker is mounted on the panelboard, the barriers 130 can fit within slots formed in the breaker housing between adjacent pole units and when single-pole circuit breakers are mounted on the panelboard they can be disposed in a close side-by-side relationship. Since the barriers 129, 130 are relatively thin, it is desirable to keep them low in height so that they will not be easily broken. With the provision of the line terminal conductors 23 extending from the bottom of the associated compartments, adequate insulation between adjacent poles is achieved with relatively low barriers 129, 130. The barrier 129, 130 are low enough that they can be molded integrally with the insulating support block 109.

Referring to FIGS. 6 and 7, a modification of the invention is shown wherein the line-terminal conductor 23 is constructed with two generally 45 bends therein rather than one 90 bend as is the case with the lineterminal conductor 23. The line-terminal conductor 23' is formed with a single reinforcing rib 125' that extends lengthwise through the two bent portions. Otherwise, the line-terminal conductors 23' are the same as the conductors 23 and they are embodied in circuit breakers in the same manner hereinbefore described.

From the foregoing, it can be understood that there is provided by this invention an improved bolt-on type circuit breaker comp-rising a re-inforced unitary line-terminal conductor that protrudes from the bottom of the breaker and is formed with the external planar end thereof being parallel to the bottom of the breaker whereby the line terminal conductor is adapted to support one end of the breaker on a panelboard conducting bar and to electrically connect the breaker contacts with the conducting bar. With the provision of the line terminal extending from the bottom, rather than from the end, of the breaker, the circuit breaker of this invention can be used in a panelboard having desirable relatively low and thin insulating barriers between adjacent poles. Certain parts of the improved breaker serve :a plurality of functions. The novel fastening means serves to fasten the line-terminal conductor and stationary contact in place and also to hold the arc extinguishing structure in place. The fastening means also serves as an arc runner to enhance extinction of the arcs drawn during circuit interruption.

While the invention has been described in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details and arrangement of parts thereof may be made without departing from the spirit and scope of the invention.

We claim as our invention:

.1. A circuit breaker comprising an insulating compartment, a pair of contacts disposed within said compartment and separable to establish an arc, a one-piece terminal conductor extending from the bottom of said compartment and being formed with the external end part thereof being generally parallel to the bottom of said compartment whereby when said circuit breaker is mounted on a panelboard said end part will engage a generally flat conducting member to physically support one end of said circuit breaker on said conducting member and to electrically connect said contacts in series with said conducting member, said circuit breaker comprising means securing said terminal conductor in place on said circuit breaker, and said securing means being constructed and arranged to serve as an arc-runner when said contacts separate.

2. A circuit interrupter comprising an insulating housing, a pair of contacts disposed within said housing and separable to establish an arc, a terminal conductor extending from said housing to permit connection of said circuit breaker in an electric circuit, means securing said terminal conductor in place, and said securing means being constructed and arranged to serve as an arc-runner when said contacts separate.

3. A circuit breaker comprising, in combination, an insulating housing, a conductor, a stationary contact secured to said conductor, means positioning said conductor to position said stationary contact within said housing, a movable contact separable from said stationary contact to establish an arc, and said positioning means being constructed and arranged to receive transfer of said are from said stationary contact when said contacts separate.

4. A circuit interrupter comprising, in combination, an insulating housing, a pair of contacts disposed within said housing and separable to establish an arc, a terminal conductor extending from said housing to permit connection of said'circuit interrupter in an electric circuit, means fastening said terminal conductor to said housing, said fastening means comprising a nut disposed within said housing and a screw member cooperating with said nut to secure said terminal conductor to said housing, said fastening means being of magnetic material and being disposed to function as an arc-runner when said contacts separate.

5. A circuit interrupter comprising, in combination, an insulating housing, a terminal conductor comprising a fiat conducting strip having one end thereof positioned within said housing and the other end outside of said housing, a contact secured at said inner end, said conducting strip having an opening in said outer end adapted to receive a screw for connecting said strip to a bus bar, means fastening said conducting strip to said housing, said fastening means comprising a member of magnetic material disposed in proximity to said contact, movable contact means cooperable with said contact to establish an arc, and said fastening means serving as an arcrunner to enhance extinction of said arc.

6. A circuit interrupter comprising, in combination, an'insulating housing, a pair of contacts disposed within said housing and separable to establish an are, an arc extinguishing structure disposed within said housing to enhance extinction of said arc, fastening means positively positioning said are extinguishing structure within said housing, said fastening means being constructed and arranged to receive transfer of said are from said stationary contact to enhance extinction of said arc.

7. A circuit interrupter comprising, in combination, an insulating housing, a pair of contacts disposed within said housing and separable to establish an are, an are extingushing structure comprising a plurality of magnetic plates positioned to draw said arc away from said contacts and to break up said are into a plurality of serially related arcs to effect extinction of said are, fastening means comprising a fastening member engaging said are extinguishing structure to positively position said are extinguishing structure within said housing, said fastening member being constructed and arranged such that as said are is drawn into said are extinguishing structure the arc is transferred from said stationary contact to said fastening member in a direction that effects elongation of the arc whereby said fastening member serves to enhance extinction of the arc.

8. A circuit interrupter comprising, in combination, an insulating housing, a pair of contacts disposed within said housing and separable to establish an arc, an arc extinguishing structure supported within said housing to enhance extinction of said arc, a terminal conductor extending from said housing to permit connection of said circuit interrupter in an electric circuit, means fastening said terminal conductor to said housing, said fastening means engaging said are extinguishing structure to positively position said are extinguishing structure within said housing, and said fastening means being constructed and positioned to serve as an arc-runner when said contacts separate.

9. A circuit interrupter comprising, in combination, an insulating housing, a pair of contacts disposed within said housing and separable to establish an are, an are extinguishing structure disposed within said housing and comprising a plurality of magnetic plates arranged to draw said are away from said contacts to lengthen said are and to enhance extinction of said arc, a terminal conductor extending from said housing, means fastening said terminal conductor to said housing, said fastening means comprising a member engaging said are extinguishing structure to positively position said arc extinguishing structure within said housing, and said fastening means being positioned to act as an arc-runner to receive the transfer of said arc from said stationary contact as said arc is drawn into said are extinguishing structure to thereby enhance extinction of said arc.

10. A circuit interrupter comprising, in combination, an insulating housing, a terminal conductor having one end thereof positioned with-in said housing and the other end extending from said housing to permit connection of said circuit interrupter in an electric circuit, a stationary contact secured to the inner end of said terminal conductor, a movable contact cooperable with said stationary contact to open and close an electric circuit, said contacts when separating establishingan arc, an arc extinguishing structure comprising a plurality of magnetic plates disposed in a spaced relationship and positioned to magnetically draw said are away from said contacts to lengthen the arc and break the arc into a plurality of serially related arcs to thereby eifect extinction of the are and interruption of said circuit, means fastening said terminal conductor to said housing, said fastening means comprising a member engaging said are extinguishing structure to positively position said are extinguishing structure within said housing, said fastening member being adjacent one of said magnetic plates and being positioned to receive transfer of said arc from said stationary contact as said are is drawn into said magnetic plates to thereby enhance extinction of said arc.

11. A circuit breaker comprising an insulating housing, said insulating housing comprising a bottom and a front opposite said bottom, a pair of cooperable contacts disposed within said insulating housing, said front having opening means therein, an operating handle extending through said opening means in said front and being operable to open and close said contacts, said bottom having opening means therein in proximity to one end of said circuit breaker, a unitary generally rigid line-terminal conductor supported on said housing and protruding through said opening means in said bottom, one of said contacts being supported on the inner part of said unitary generally rigid line-terminal conductor, said unitary generally rigid line-terminal conductor at the outside of said housing extending below the lowermost part of said housing and being shaped to provide an external end part thereof disposed along a plane generally parallel to said bottom, said external end part comprising a connecting part, said connecting part extending away from said housing below the lowermost part of said housing and having opening means therein, said connecting part and opening means being disposed outside the fr-ont-elevational-view dimensions of said housing, whereby said circuit breaker can be mounted on a generally flat conducting connector of a panel board with said external end part, engaging said conducting connector to provide physical support for said one end of said circuit breaker on said conducting connector and to electrically connect said contacts in series with said conducting connector and whereby said opening means is accessible from the front of said circuit breaker to receive a securing member that may be used' to' removably secure said connecting part to said conducting connector.

12. A circuit breaker according to claim 11, said unitary generally rigid line-terminal conductor comprising a sheet-metal type conducting member having reinforcing rib means formed thereon integral therewith.

References Cited by the Examiner UNITED STATES PATENTS 2,976,385 3/1961 Edmunds 3'17119 3,025,376 3/1962 Yarrick 200-444 3,073,926 1/1963 Ellsworth et al. 200'88 3,073,927 1/1963 Hill et al. ZOO-88 3,133,999 5/1964 Zubaty et al. 2001 16 ROBERT K. SCHAEFER, Primary Examiner.

KATHLEEN H. CLAFFY, ROBERT S. MACON,

Examiners, P, CRAWFORD, Assistant Examiner, 

3. A CIRCUIT BREAKER COMPRISING, IN COMBINATION, AN INSULATING HOUSING, A CONDUCTOR, A STATIONARY CONTACT SECURED TO SAID CONDUCTOR, MEANS POSITIONING SAID CONDUCTOR TO POSITION SAID STATIONARY CONTACT WITHIN SAID HOUSING, A MOVABLE CONTACT SEPARABLE FROM SAID STATIONARY CONTACT TO ESTABLISH AN ARC, AND SAID POSITIONING MEANS BEING CONSTRUCTED AND ARRANGED TO RECEIVE TRANSFER OF SAID ARC FROM SAID STATIONARY CONTACT WHEN SAID CONTACTS SEPARATE. 